Bill and Mary first met as children. They lived next door to each other, the shy boy with glasses and the spitfire girl with red hair. Bill used to knock on Mary's door every afternoon, and ask in his shy voice, "Can Mary come out to play?" And Mary would always come rushing out to play with Bill, without fail, until their parents called them in for dinner.

They spent so much time together that, as they grew older, it was natural that Bill and Mary would start to develop a greater interest in each other. Bill grew up to become a tall, confident teenager, while Mary blossomed into a ravishingly beautiful redhead. Soon, Bill would knock on Mary's door, but instead of asking if she could come out to play, he would ask, "Is Mary ready yet? The movie starts in half an hour." And Mary would come charging out the door, greeting Bill with an embrace and a kiss.

Their relationship continued all through high school, but then they both went away for college, and the distance made romance untenable. It was often weeks before they could visit each other, brief trips squeezed in on weekends or holidays. Inevitably, they drifted apart, and other people entered their lives. And so Bill and Mary broke up amicably, with both agreeing that they were happy to have been each other's first love.

Bill soon met Wendy. In many ways, Wendy reminded Bill of Mary. Wendy and Mary looked rather alike, with their flowing red hair, and they had similarly firey personalities. Bill and Wendy started dating in college, and continued after graduating. They settled down in their careers, and soon the topic of marriage came up. Not long after that, Bill knelt down in front of Wendy and presented her with a diamond ring.

And yet, in some deep, hidden corner of Bill's heart, he wondered if he wasn't really marrying Wendy. He wondered if he still loved Mary, and that Wendy was, at best, a substitute for that dynamic red-haired girl from his childhood. He never said a word to Wendy about Mary, never mentioned her once. He knew that Wendy was smart enough to see through him if he wasn't careful.

Wedding planning took up a good chunk of Bill and Wendy's time together for the next few months. Visiting and booking venues, trying on dresses, dealing with the food and drink and flowers and invitations. The guest list was the most time-consuming part, and Bill and Wendy spent many evenings trying to trim the number of guests to an amount that would fit in the venues they'd ultimately decided on.

On one such evening, as Bill and Wendy went through Bill's side of the aisle, Wendy noticed a name on the list. "Mary Flanders? Who's that?"

"Oh, a friend of mine from when I was a kid. She lived next door," Bill replied.

"She's just a neighbor from when you were a kid? Are you sure you want to invite her?"

"Yes, of course I'm sure," Bill answered, a bit too quickly.

Wendy narrowed her eyes briefly at Bill, then nodded and moved on.

Soon the big day was approaching. Everything was falling into place. And then two days before the wedding, Bill received an email from Mary.

Hi Bill!

I'm going to be in town for your wedding, but I'll be arriving a day early, to handle some business. Let's have dinner tomorrow night, your last night of freedom, and catch up a bit! What do you say? It's been, what, five years since we've seen each other? We've got a lot of catching up to do!

Bill didn't even hesitate to reply.

Mary! Sure, dinner sounds great! Let's meet at 6 at Angelo's, I know you know the place! :)

It was only after he clicked "send" that Bill realized he had no idea if he should tell Wendy about this. Surely there would be no issue with telling Wendy, she would have no problem with it, right? Like Wendy had said, Mary was just a neighbor from when he was young, right? She's just a friend. Surely there's nothing wrong with grabbing a bite with an old friend? It's just dinner, it doesn't mean anything.

But then Bill remembered that narrowed gaze Wendy had given him, not too long ago. His justifications suddenly sounded incredibly hollow even to himself. No, Bill decided, there's no need to tell Wendy. There'd be too much to explain, and it would just trouble her unnecessarily.

The next evening, Bill was at Angelo's at five fifty-five sharp. He stood in front of the restaurant, inexplicably nervous. Five years was a long time to have never seen each other, and a lot can change in five years. What was Mary like now? Was she still the feisty firecracker she'd been in her youth?

And then Mary came around the corner, and it was as if the last half decade had never happened at all. She was still ravishingly beautiful, with her red hair and clever grin. Bill found himself grinning back at her. They met in an embrace, exactly like when they were teenagers. It was as if their past five years apart had never happened at all.

Dinner went by in a blur. Bill later realized that he had no recollection of what he'd ordered or eaten. He was too busy staring at Mary, and talking to her, and laughing with her. He knew Mary well enough to know that she felt the same way.

They stayed at Angelo's until closing time, talking and laughing. Afterwards, Bill walked Mary back to her hotel. In the hotel lobby, Mary gave Bill another hug, then said, "Bill, this was great. I'm sure you'll have an amazing wedding tomorrow, and you'll be a great husband to Wendy."

"Thanks," Bill replied. "I'll do my best, that's for sure."

Mary paused for a moment, then said, "Of course, there's still the million dollar question, isn't there? I know you've been thinking it too. Would you be happier with me? The girl from your childhood, your first love, the one who's been with you the longest and knows you the best?"

Bill pondered for a moment before answering as truthfully as he could. "Well, Mary, to be honest I think it would've been amazing. I honestly do. I think we'd be happy with each other. But we had our shot. I'm marrying Wendy tomorrow, she's the one I've decided to spend the rest of my life with, so there's no point thinking too much about the what-ifs and maybes."

Mary smiled dazzlingly in satisfaction. "Yeah, that's the Bill I know. I knew you wouldn't hurt Wendy like that. And you're right, we had our shot, and it was a good run. We'll always have the happy memories. But it's time to move on. To be honest, if you said you'd abandon Wendy to be with me, I would've been so disgusted at you I'd turn around and walk away."

Bill had to grin at that. "That sounds entirely like something you'd do, Mary."

Mary grinned back, then stuck out a hand. "Well. Good night, friend."

Bill shook Mary's hand with a dramatic flourish. "Good night indeed, my friend. See you tomorrow!"

It was nearly midnight by the time Bill got home, but oddly enough the lights were still on. "That's strange," Bill thought to himself, "Wendy should be asleep now."

Wendy was waiting for Bill in the living room. "Where were you?"

"What do you mean?" Bill asked.

"Where were you tonight? Who were you with?" Wendy's voice was completely calm, which Bill knew was a bad sign. Wendy was usually so exuberant, but she only became calm when she was truly upset.

"I was having dinner with an old friend..." Bill tried to say, but Wendy cut him off.

"You were with a woman!" Wendy spat. "I saw you, Bill! I was in town to pick up some last minute things, and I passed by Angelo's, and I saw you and that redhead through the window, sitting in there together. And I waited outside until you came out, and you didn't even notice me! I followed the two of you to a hotel! A hotel, Bill!"

Bill raised his hands defensively, "Okay, yes, yes I was with a woman. She's an old friend of mine, here for the wedding, and we were just catching up, and then I walked her back to her hotel. That's all!"

"That's Mary, isn't it?" Wendy asked, with the same narrowed gaze from months ago.

Bill saw no point in trying to deny it. "Yes."

"You loved her, didn't you."

"Yes."

"And she loved you."

"Yes."

"But you can't have her, so I'm just a replacement for her."

"What? No... no..." Bill sputtered. His denial sounded insincere even to him.

Wendy glared at Bill. "Don't try to deny it. Don't try to lie to me. She even looks like me. I'm just Mary two-point-oh to you, aren't I? You can't have her, so you'll settle for me."

"No, Wendy, listen to me. Yes you're right, Mary and I did have a relationship, but it was a long time ago. I hadn't even talked to her in years! No matter what happened in the past, you're the one I'm with now, just you, Wendy," Bill said, "So please, believe me, you're absolutely the one I want to be with."

Tears were streaming down Wendy's cheeks. Bill couldn't recall ever seeing her cry. Wendy said, "But just seeing you with her... seeing you talking and laughing... how am I supposed to get that out of my head? What if one day you decide you don't want Mary two-point-oh, you want the real one? What if you hate me for depriving you of the life you really wanted? What if you can't even look at me? We'd be this weird married couple, where you'd just ignore me all day long, you wouldn't even be able to take a peek at me."

Bill gathered Wendy in his arms and held her sobbing body to his. "Oh Wendy, Wendy... don't be silly. Of course I won't hate you. Of course I won't start wishing for a life I can't have. That's silly. You're the one I choose to be with, Wendy. Just imagine! Us, not being able to look at each other? Not even a peek? Of course that's not going to happen. Of course I'd be able to peek at you. I choose you!"